Male South American Comb Duck (Sarkidiornis melanotos sylvicola) Found in continental South America south to the Paraguay River region in eastern Paraguay, southeastern Brazil and the extreme northeast of Argentina. Stock Knob billed duck (Sarkidiornis melanotos) in flight. From Sub Saharan Africa, Madagascar, and Indochina. : r AIDKE Photos Knob billed Duck Sarkidiornis melanotos Birds of the World The knob billed duck (Sarkidiornis melanotos) aka African comb duck, is found in tropical wetlands in Sub Saharan Africa, Madagascar and the Indian Subcontinent from northern India to Laos and extreme southern China. Sarkidiornis melanotos (Comb duck, Knob billed duck)